Nuclear magnetic resonance relaxation measurements using the halogen ions has developed as an excellent method for measuring important properties of metal ions in solution. Classification of the zinc enzymes on the basis of metal coordination will be possible from these experiments. For those in the class providing halide ion access to zinc, measurements of the zinc halogen ion equilibrium constants will be made for the chloride ion complexes. Determination of the acidity or ionization constant for water molecules coordinated to zinc will be made from the pH dependence of the halogen ion nmr line width. Rates of the metal halogen exchange reactions will be measured for the zinc enzymes and the factors which control these exchange rates will be determined. Specific enzymes under study include carbonic anhydrase, carboxypeptidase and liver alcohol dehydrogenase. In addition to the study of the zinc enzymes magnetic resonance investigations of metal-protein interactions employing other nuclei magnetic resonance techniques will be undertaken. These measurements will include alkali metal and alkaline earth metal nmr measurements in a variety of systems. BIBLIOGRAPHIC REFERENCES: R. J. Smith and R. G. Bryant, Biochem. Biophys. Res. Commun., 66, 1281(1975) "Metal Substitutions in Carbonic Anhydrase: A Halide Ion Probe Study". R. S. Stephens and R. G. Bryant, J. Biol. Chem. 251, 403(1976). "Zinc Chloride Ion Exchange Rates in Carboxypeptidase A".